Source: Times.com When it comes to preventing pregnancy, the burden falls largely on women. But that responsibility could soon shift, according to new research from Columbia University that raises the tantalizing prospect of a male birth control pill. The key to a pill for men may lie in vitamin A, which is necessary for the growth of sperm cells. When researchers working with mice administered an experimental medication that interfered with receptors needed to metabolize vitamin A, male mice lost their fertility. Shortly after the animals stopped taking the compound, they resumed mating and making babies successfully. Sasa wale watani zangu walevi watasahau kila siku kunywa pills.